The present application relates generally to seal assemblies for turbo-machinery and more particularly relates to film riding seal assemblies for sealing rotor-stator gaps and the like.
Various types of turbo-machinery, such as gas turbine engines, aircraft engines and steam turbines are known and widely used for power generation, propulsion, and the like. The efficiency of the turbo-machinery depends in part upon the clearances between the internal components and the leakage of primary and secondary fluids through these clearances. For example, large clearances may be intentionally allowed at certain rotor-stator interfaces to accommodate large, thermally or mechanically-induced, relative motions. Leakage of fluid through these gaps from regions of high pressure to regions of low pressure may result in poor efficiency for the turbo-machinery. Such leakage may impact efficiency in that the leaked fluids fail to perform useful work.
Different types of sealing systems are used to minimize the leakage of fluid flowing through turbo-machinery. The sealing systems, however, often are subject to relatively high temperatures, thermal gradients, and thermal and mechanical expansion and contraction during various operational stages that may increase or decrease the clearance therethrough. For example, traditional labyrinth seals that are assembled to run very tight clearance during start-up transient phase might run with large clearances during steady state operations, thereby leading to poor performance at steady state operation.
There is therefore a desire for improved compliant sealing assemblies for use with turbo-machinery for sealing rotor-stator gaps. Preferably such compliant sealing assemblies may provide tighter sealing during steady state operations while avoiding rubbing, wear caused by contact and damage during transient operations. Such sealing assemblies should improve overall system efficiency while being inexpensive to fabricate and providing an increased life for the associated parts.